1. Field of the Invention
The present invention relates to a support for retaining biomedical implant devices such as a catheter for peritoneal dialysis, an extracorporeal shunt for hemodialysis, a tube for an ascites recirculation circuit, a drain tube, an air tube for an artificial heart, an electric circuit tube, and drug reservoir to be implanted under the skin. In particular, the present invention relates to a support for such biomedical implant devices that manifests enhanced biocompatibility and which allows them to be retained in the body over a prolonged period without permitting bacterial ingress.
2. Background of the Invention
An example of the support conventionally used to fix a biomedical implant device in the human body is a cuff which is used with a catheter for peritoneal dialysis. As shown in FIG. 1, a catheter 1 is inserted through the skin 10 of the patient, the subcutaneous layer of fat 11, the fascia 12, the muscular tunic 13 and the peritoneum 14. The catheter 1 is retained in the body so as to permit injection or discharging of a dialyzing solution through the catheter 1. In this case, a cuff 2 attached to the catheter 1 is used as a support for functionally retaining the catheter 1 in the body over an extended period and is generally sutured in living tissues at the end of a surgical operation. The cuff 2 is typically made of such materials as knitted or unknitted fabrics of synthetic or natural fibers, plastic or plastic film.
Another prior art biomedical implant device proposed to date is a drug reservoir for subcutaneous implantation. As shown in FIG. 2, a reservoir 15 is implanted below the skin layer 10 and is composed of a drug cell 16. Holes 17 on projections guide a retaining thread (suture). The intended drug is injected into the cell 16 through a silicone or synthetic rubber wall 18. A silicon tube 19 serves as a passage for introducing the drug into the affected site of part of the body such as a blood vessel or muscle. Stability of the retained reservoir 15 is required for a prolonged period in order to allow for periodic supply of the drug into the reservoir through the wall 18 with syringe.
Conventional supports such as cuffs that are formed of cellulosic or synthetic fibers, plastics, titanium or silicone resins show poor biocompatibility and poor adhesion to living tissues because of the nature of their constituent materials. As a result, during prolonged use of biomedical implant devices within the body, they might be displaced in position or bacterial ingress may occur in the gap between the device and the surrounding tissues.